A recorded open shows that an image was requested. Privacy services can make that request before a person reads the message. A person can also read with images blocked and produce no open event.
How does open tracking work?
An email platform adds a transparent tracking image to the HTML message. Its URL identifies the message and recipient, so the tracking server can associate an image request with that send.
When a client loads the image, the server records an open event. The event can include the request timestamp, IP address and user agent. These describe the request; a proxy can hide the recipient's own device or location. Bird's open and click tracking guide describes the recorded events.
Why is open tracking unreliable?
Automatic image fetching can record an open without reading. Blocked images and plain-text messages can hide a real read.
Apple's Mail Privacy Protection downloads remote content in the background regardless of whether the recipient engages with the email. It also hides the recipient's IP address. An open caused by that fetch cannot establish that the person read the message.
A recipient who blocks remote images can read the text without loading the tracking image. A plain-text message carries no tracking image. Neither produces the image request needed to record an open.
Compare opens only with the audience, tracking settings and privacy effects in view. A change in the recorded rate identifies something to investigate; it does not establish a change in reading or inbox placement.
What does a click establish?
A tracked click establishes that a client requested a rewritten link. It does not establish who made the request or whether they completed the intended action.
Click tracking redirects requests through a tracking server before continuing to the destination. It works without loading an image. Anti-spam systems can also follow links, as Spamhaus, an email blocklist publisher, describes.
For a purchase campaign, measure completed purchases in your application alongside recorded clicks. For account setup, measure completed setup. Keep the audience and comparison period consistent. Clicks can help locate a change in the journey, but the completed action establishes the result you wanted.
How do you enable or disable open tracking with Bird?
You enable open tracking for your sending domain and verify its tracking hostname. The per-message track_opens flag must also be enabled. Its API default is true, but that flag alone does not enable domain tracking.
Set track_opens: false on a message to prevent the tracking image. Configure track_clicks separately; disabling opens does not disable click tracking. The send request reference defines both boolean flags, and the tracking guide explains the domain prerequisites.
You can inspect email.opened events and their is_prefetched field through the events API. Bird excludes identified prefetched opens from the dashboard's unique open rate. Filtering still cannot count a person who reads with images blocked.
Can a delivered email still miss the inbox?
Yes. The receiving mail server can accept a message and place it in spam. The email.delivered event records that server acceptance. It does not establish inbox placement or reading.
Inbox Insights provides placement estimates from sampled mailboxes. Delivery events report the sending lifecycle separately. A receiving server can also issue a late bounce after accepting the message, so an initial delivery event does not exclude a later failure.